feat(api): add OIDC session service (#6157)

This PR starts the OIDC implementation for the API V2 including the Implicit and Code Flow.


Co-authored-by: Livio Spring <livio.a@gmail.com>
Co-authored-by: Tim Möhlmann <tim+github@zitadel.com>
Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>

internal/api/grpc/oidc/v2/server.go

@@ -0,0 +1,59 @@
+package oidc
+
+import (
+	"github.com/zitadel/oidc/v2/pkg/op"
+	"google.golang.org/grpc"
+
+	"github.com/zitadel/zitadel/internal/api/authz"
+	"github.com/zitadel/zitadel/internal/api/grpc/server"
+	"github.com/zitadel/zitadel/internal/command"
+	"github.com/zitadel/zitadel/internal/query"
+	oidc_pb "github.com/zitadel/zitadel/pkg/grpc/oidc/v2alpha"
+)
+
+var _ oidc_pb.OIDCServiceServer = (*Server)(nil)
+
+type Server struct {
+	oidc_pb.UnimplementedOIDCServiceServer
+	command *command.Commands
+	query   *query.Queries
+
+	op             op.OpenIDProvider
+	externalSecure bool
+}
+
+type Config struct{}
+
+func CreateServer(
+	command *command.Commands,
+	query *query.Queries,
+	op op.OpenIDProvider,
+	externalSecure bool,
+) *Server {
+	return &Server{
+		command:        command,
+		query:          query,
+		op:             op,
+		externalSecure: externalSecure,
+	}
+}
+
+func (s *Server) RegisterServer(grpcServer *grpc.Server) {
+	oidc_pb.RegisterOIDCServiceServer(grpcServer, s)
+}
+
+func (s *Server) AppName() string {
+	return oidc_pb.OIDCService_ServiceDesc.ServiceName
+}
+
+func (s *Server) MethodPrefix() string {
+	return oidc_pb.OIDCService_ServiceDesc.ServiceName
+}
+
+func (s *Server) AuthMethods() authz.MethodMapping {
+	return oidc_pb.OIDCService_AuthMethods
+}
+
+func (s *Server) RegisterGateway() server.RegisterGatewayFunc {
+	return oidc_pb.RegisterOIDCServiceHandler
+}